Broken small-block slide carb

[fstnd]

Hello, today I've put in and set all the electronics to my new RC. I confirmed the engine started for 4 seconds but that's it. Guess what? My fourth carb with a problem. They must hate me. Here some pics:

I know I know, the throttle setup is awesome, but please help. Is there a cheap replacement carb? If there is any way to repair this massive crack in the old carb please tell me.

This crack was already there before I bought it. But when I screwed it in, which didn't even need any force, it broke even further.

Total diameter of the carb where airfilter is hooked up: 11mm
Total diameter of the other side of the carb that goes into the engine:i guess 10mm(hard time measuring due to crack)

I'm talking about the diameter of the whole, not the hole

 

[tntpoof]

try alumiloy.its worked for me..aluminium low temp welding rods and propane torch

 

[tudordewolf]

You're in luck, Sh.18 slide carbs are in stock right now. They have a 10mm "neck", pretty universal and should fit yours fine. Only challenge might be their slightly larger air-filter port, you'll need a slightly larger air filter boot to fit it.

 

[alfredwong2003]

I think it has to do how you install the throttle linkage, it put a lot of stress on the carburetor, I converted from a rotary to a sliding engine like the photo below.

 

[fstnd]

try alumiloy.its worked for me..aluminium low temp welding rods and propane torch

Hey thanks, do you think this will do the job?

not necessarily because I'm on the cheap but I prefer to keep everything by aliexpress. But how do you do this? Just melt it on the crack to stiffen or does it need to be in perfect shape to be airtight? Or O'rings?

You're in luck, Sh.18 slide carbs are in stock right now. They have a 10mm "neck", pretty universal and should fit yours fine. Only challenge might be their slightly larger air-filter port, you'll need a slightly larger air filter boot to fit it.

Thanks, filter part won't be a problem, I have 3 or 4 different mall block filters currently surely one of them will fit or I'll make them fit anyway.
This can be by "plan-b" for now, if the welding won't work. This SH option could be better but I'm curious and just want to try that welding stuff, I never tried it before.

I think it has to do how you install the throttle linkage, it put a lot of stress on the carburetor, I converted from a rotary to a sliding engine like the photo below.View attachment 166729

Nice option aswell, I have a second-hand protech nitro engine nearby with a slide carb but the owner doesn't tell me if its small or big block. It looks more like a big block to me. This is what I can do to convert my slide carb to a roto carb, but most likely I'll rather go with plan B.
Thanks

 

[NitroR/C]

Surely something cheap can be found on Ebay but you have to see with the measurements.

https://www.ebay.co.uk/b/RC-Exhaust...ow-Fuel-Cars-Motorcycles/182190/bn_7031949445

 

[tntpoof]

https://www.amainhobbies.com/sh-engines-.18-complete-slide-carburetor-shete1809b/p524232

cheaper than my fix

 

[fstnd]

Sorry for annoying you with Aliexpress, but I'd love it too if aMain shipped to europe... NitroR/C the link worked the first time I clicked, but maybe it's sold now??
Anyway, would this carb fit:
https://a.aliexpress.com/_mKYQQ6k
Do the trx 2.5 2.5r and 3.3 engines have slide carbs and do they have the right measurement?

 

[tudordewolf]

Sorry for annoying you with Aliexpress, but I'd love it too if aMain shipped to europe... NitroR/C the link worked the first time I clicked, but maybe it's sold now??
Anyway, would this carb fit:
https://a.aliexpress.com/_mKYQQ6k
Do the trx 2.5 2.5r and 3.3 engines have slide carbs and do they have the right measurement?

Those have 13mm carb necks, it would not fit. (also that particular carb is a bit... difficult) Amain has an ebay page, would this listing ship to you?

Edit: If not, here's another. The part number is TE1809B / TE1809B2

I think it has to do how you install the throttle linkage, it put a lot of stress on the carburetor, I converted from a rotary to a sliding engine like the photo below.View attachment 166729

I really like that improvised bellcrank, I might copy that into one of mine.

 

[fstnd]

Thanks
I'll probably go with the first link

I think it has to do how you install the throttle linkage, it put a lot of stress on the carburetor, I converted from a rotary to a sliding engine like the photo below.View attachment 166729

I just realised we have exactly the same car lol, do you know the name of its model? Because I don't

 

[tudordewolf]

Thanks
I'll probably go with the first link

I just realised we have exactly the same car lol, do you know the name of its model? Because I don't

I've seen that top brace before, I think it's a Smartech Winner?

 

[NitroR/C]

As a carburetor, perhaps it would be better rotary instead of slide--making a Gas/Brake linkage configuration like this.

 

[NitroR/C]

as you can see from this video, everything flows properly.

 

[fstnd]

I just replaced the broken carb with a rotary. It didn't start for a long time, but now it finally started after some tuning and glowplugging. BUT something keeps leaking

what could this be?? Please note this is not unburned oil residue: this is pure, wasted fuel. I have a video that I'll soon edit into this message. It idled at full carb throttle...

https://www.mediafire.com/file/d8bgf3gwttxiuyg/lv_0_20230603134316.mp4/file

 

[NitroR/C]

This looks more like mixture and oil coming out of the front bearing to me, too thick to be pure mixture.This also explains the too rich (fat) carburetion in my opinion.
Optimal engine carburation may seem like an insurmountable obstacle, but it is actually quite
simple, all it takes is a little ear and a good understanding of how a carburetor works. First warm up the
engine for a couple of minutes with light acceleration. Adjust the mechanical idle speed: When the
engine is warm, about 85 to 100°, keep the carburetor at idle speed (with the throttle or pad
all closed) and adjust the screw stop until the engine reaches a smooth rpm
(around 1500 rpm). The Carburetor has 3 main adjustments: the idle pad needle
which adjusts the engine when it starts from a standstill or at low speed up to its medium speed; the needle of the
maximum which adjusts the engine at medium-high speeds i.e., at maximum speeds and accelerations with the engine
in torque; the idle needle that adjusts the carburetion of the engine at the medium-low speeds, i.e., during
acceleration. TIP Always adjust the maximum needle so that the engine with the
carburetor open to maximum makes a fair amount of smoke in a straight line as a demonstration of a carburetion
"rich" or "fat" CAUTION !!!! because using the engine in a condition of carburetion of the maximum
"lean" you risk damaging it due to lack of lubrication. Static carburation: At this point
proceed with a little more vigorous accelerations so that you can perceive in sound of the engine at a
higher rpm level. If it "hiccups" or revs up very quickly (even before
you have given it full throttle) the carburetion is "lean," the volume of mixture being introduced into the
combustion chamber is not sufficient for the needs of the engine. You need to unscrew the maximum needle until you reach
a more even sound than the engine itself, and the muffler should emit a fair amount of smoke. If
on the other hand, the engine has difficulty revving up, "mumbles," spits a lot of smoke from the exhaust along with oil, the
carburetion is "fat," that is, too much volume of mixture enters the combustion chamber and the engine
fails to burn it. Tighten or tighten the screw of the maximum needle until the amount of
smoke given off from the exhaust and until a smoother engine sound and higher engine speed are achieved.
high. Carburetion on the move: At this point you must perform carburetion with the model in
motion by running on a track. The engine symptoms are the same but now we have an extra help, the
model is affected by the behavior of the engine so carburetion is now easier. Make a
couple of laps to reach operating temperature always making sure that at full throttle it comes out
A fair amount of smoke from the exhaust. Carburetion of the idle needle: At this point try
stopping the model for 3-4 seconds and then try starting quickly. If the engine hiccups and has
difficulty starting, the idle rises and there is no smoke emission from the exhaust, the carburetion is
"lean idle," unscrew the needle until the start and engine sound improve.
Try stopping the model for 3-4 seconds and then try starting quickly. If the engine hiccups
and has difficulty starting, the idle rises and there is no smoke emission from the exhaust, the carburetion is
"lean idle," unscrew the needle until the start and engine sound improve. If
on the other hand, the engine has difficulty revving up, spits out a lot of smoke or shuts down when you wait at
idle, then it is "idling fat"-screw the needle until the engine sounds progressively
like a hissing sound with a slight smoke emission. Here is the last step the carburetion of the needle of the
maximum: make two or three runs under these conditions and adjust the maximum needle so that the
engine has a steady acceleration to the end of the straight line with a hiss throughout.
Make another 2 or 3 laps if the engine does not drop in performance at the end of the straight or on fast turns
under maximum effort then the carburetion is OK! In case of loss of power and drop in rpm unscrew the
maximum needle (grease the carburetion) by about 2mm and try again until the constancy of
performance.

 

[cbaker65]

I just replaced the broken carb with a rotary. It didn't start for a long time, but now it finally started after some tuning and glowplugging. BUT something keeps leakingView attachment 166789View attachment 166790View attachment 166791View attachment 166792what could this be?? Please note this is not unburned oil residue: this is pure, wasted fuel. I have a video that I'll soon edit into this message. It idled at full carb throttle...

https://www.mediafire.com/file/d8bgf3gwttxiuyg/lv_0_20230603134316.mp4/file

First time that I ever seen a carb chewed up like that ,your front bearing may have something to do with that ,
that maybe the reason why it is hard to start ,it throws the ignition off!..

 

[alfredwong2003]

Thanks
I'll probably go with the first link

I just realised we have exactly the same car lol, do you know the name of its model? Because I don't

It was a smartech.

I just replaced the broken carb with a rotary. It didn't start for a long time, but now it finally started after some tuning and glowplugging. BUT something keeps leakingView attachment 166789View attachment 166790View attachment 166791View attachment 166792what could this be?? Please note this is not unburned oil residue: this is pure, wasted fuel. I have a video that I'll soon edit into this message. It idled at full carb throttle...

https://www.mediafire.com/file/d8bgf3gwttxiuyg/lv_0_20230603134316.mp4/file

I would also check to make sure the exhaust header gasket is in good shape.

 

[NitroR/C]

I had missed that... the side exhaust. how many times on a rtr with a broken gasket or loose screws they caused me an oil contamination.

 

[gandalfnz]

That looks like a typical bad front bearing leak.
They will do this if the engine is over primed.
With a leak that bad, you will need to replace it.

 

[NitroR/C]

That looks like a typical bad front bearing leak.
They will do this if the engine is over primed.
With a leak that bad, you will need to replace it.

That was the first thing I thought as soon as I saw the pictures--the centrifugal force of the flywheel, it shoots oil everywhere. Rubber shielding lost seal by wearing out due to bearing play. But as mentioned before, it could also be the exhaust manifold gasket. Need to clean it and see at oil leakage with model running but on dyno.
If the engine is now already at its end, many times it is not worthwhile to repair it but to replace it with a new one (I am talking about this kind of inexpensive engines) example this one at definitely affordable prices.

https://www.ebay.de/itm/32567245376...xiJ9XWDat7rMwrVemED7MubXvk|tkp:Bk9SR-Ti1tKQYg